By MELANIE MCFARLAND, P-I TELEVISION CRITIC

Updated 10:00 pm, Thursday, March 8, 2007

In a few weeks, when the final episodes of "The Sopranos" hit the air, we'll begin reading stories about all the ways in which the series changed television. Rightly so. HBO came to represent television at its best, inspiring other networks to raise their ambitions. The most successful transformation has to be FX, the basic cable network that built up its reputations on the combined strengths of "The Shield," "Nip/Tuck," "Rescue Me" and "30 Days."

Monday night, the channel introduces "The Riches," a drama about a family of traveling con artists from the backwoods of Louisiana, a show that vacillates between riveting and middling in its first three hours.

"The Riches" premieres strongly, with casting tailored to grab our attention. Two famous Brits, Eddie Izzard and Minnie Driver, play Wayne Malloy, the charming head of household (the house in question being a tattered R.V.), and his wife, Dahlia.

The Malloy kids are budding grifters, especially jaded Dehliah (Shannon Woodward) and moody Cael (Noel Fisher). Youngest child Sam (Aidan Mitchell) is a highly intelligent kid who likes wearing his sister's old clothes. As Gypsy Travellers, they hold to a set of superstitions and laws, one being that if you sleep indoors you risk losing your soul.

Quirks glued in place, we launch toward a level of complexity that evokes premium content as opposed to basic expectations. As it opens, a confident Wayne saunters into a class reunion, wearing another man's nametag, making conversation and parting the clueless "buffers" (the term for non-Traveller folk) from their wallets. He's a nice enough guy, and his kids love him.

From there, it's on to prison to pick up Dahlia, looking nothing like her name -- gray-skinned, mangy and ornery, Dahlia carries a souvenir from the pokey in the form of a drug habit. A hell of a transformation on Driver's part.

"The Riches" is a leap in other ways as well. It's the first series from playwright Dmitry Lipkin, a man with a biography almost as interesting as his series.

Born in Russia, he moved to the Southern U.S. at age 10 and learned English from sacking out in front of his television, and it's obvious he picked up the form's language as part of those studies.

Constructing a series about people off society's grid comes naturally to him. However, he could be in for an unpleasant lesson in viewer fickleness when it comes to criminals.

The Malloy family, pleasant as they come across, are thieves. No getting past that. Meeting the rest of the Traveller clan, soon to be led by a reckless, violent cousin named Dale (Todd Stashwick), makes Wayne and Dahlia seem like rascals in comparison.

That's the key, isn't it? We have to buy these bad, bad people as flawed but not unredeemable, fallible men and women somehow driven in spite of their humanity to do the terrible things they do.

Maybe that quality will help Wayne win over viewers, since he makes it clear he considers himself to be better than the rest of his ilk -- more intelligent, more cultured, and more deserving of success. He has the bricks and mortar of the American dream in his hands.

When his opportunity comes knocking, it takes the form of a left-field twist some people may find too repugnant to accept.

It's a wrenching scene. The kind that makes you clap your hand over an open mouth. But this fateful development allows the tricksters to slide, somewhat cleanly, into the buffer life. The Malloys become The Riches, moving into an exclusive luxury community with unusually friendly neighbors led by the curious Nina Burns (Margo Martindale).

Themes like these don't always pay off below the premium tier, particularly in a medium in which the greatest successes are ones that operate on classic engines. USA's "Monk," TNT's "The Closer," these are scripted series propelled by unconventional and beloved characters. Take away their central draws, and you have two run-of-the-mill cop shows.

Everybody loves cop shows. FX has to acknowledge that; the series that put it on the map is "The Shield." The question is, will enough people welcome the Malloys?

That's a tough one. "The Riches" operates on an improbable conceit from the outset, one Lipkin sells very well in that first hour. Izzard's Wayne is quite the smooth operator at the top of his game in many social situations, and the actor makes him lots of fun to watch.

One caveat to that enjoyment is that you have to ignore his wandering American accent; Izzard slides around in his non-regional American enunciation, and if you listen closely to it (something you might do if you're familiar with his other work), the flaws can overwhelm the dialogue.

To be fair, his attempt trumps Driver's drawl, with inflections hauled straight out of some old cartoon about the Hatfields and McCoys.

Plot direction of subsequent episodes, though, is more likely to erode feelings of good will by attempting to sell ever-more implausible situations.

Doug Rich, the man Wayne is impersonating, is in a profession few people, even that kid in "Catch Me If You Can," could believably walk into. He gives it a shot, stumbling through an awkward, stop-and-go interview speech, and what is supposed to be a humorous interlude falls dead.

But the producers keep at it, getting Wayne, Dahlia and the kids deeper and deeper into their glamorous lie and serious expenses, and away from the truth of who they are.

This is the screenwriting equivalent of filling a field with bear traps, hoping to gather us in a cycle of anxiety as we return time and again to see how they'll get themselves out of this one, and that one, and the other thing.

That could be the nagging interior voice that wants to dismiss "The Riches" as another earnest jolt of dark and strange from the anti-hero network. Indeed, the price of being set among television's top-shelf programming is that any wobbling leads to a perhaps undue amount of distrust from the viewing faithful. A fall from such heights -- say, in the form of a clod like "Dirt" -- can halt momentum cold.

Enough goes right with "The Riches," however, to allow for a cautionary amount of faith that the series can do right by us. Some have complained about FX's style, considering its explorations of gray areas and shadiness to have a rote predictability. But it does engrossing, wonderful weirdness in a way no other basic cable network does.